With traveling work vehicles such as tractors, gear-shifting control units that create 20 or more vehicle gear ratios by combining a main gear-shifting apparatus and a sub gear-shifting apparatus in order to obtain speeds (vehicle speeds) that are suitable for various types of work traveling and road traveling have also become widespread. In such a case, the gear-shifting operation method for the main gear-shifting apparatus and the method for the sub gear-shifting apparatus are different, and there are known to be vehicles in which a main gear-shifting operation lever and a sub gear-shifting operation lever are included separately, and vehicles in which an operation button that enables a gear-shifting operation of one gear-shifting apparatus is provided on an operation lever for the other gear-shifting apparatus.
For example, JP 2008-57674A discloses a work vehicle that includes a main gear-shifting apparatus having eight gear stages, and a sub gear-shifting apparatus having three gear stages. With the main gear-shifting apparatus, the gear stage of the main gear-shifting apparatus is determined using a main gear-shifting lever that can be operated to gear shift positions for a first gear stage to an eighth gear stage. With the sub gear-shifting apparatus, the gear stage of the sub gear-shifting apparatus is determined using a sub gear-shifting lever that can be operated to three gear shift positions. The operation position of the main gear-shifting lever is displayed on a display portion divided into seven segments, and thus the driver can set the desired gear stage out of the eight gear stages while viewing the display portion.
Furthermore, JP 2009-214877A discloses an agricultural tractor that includes a main gear-shifting apparatus that obtains eight gear stages by combining a first main gear-shifting apparatus with four gear stages and a second main gear-shifting apparatus with two gear stages, and a sub gear-shifting apparatus that is capable of three-stage gear shifting. When the sub gear-shifting apparatus is operated, a main clutch engagement/disengagement operation is needed, and therefore a main clutch pedal is stepped on, the operation lever is operated in a front-rear direction or a left-right direction, and the main clutch pedal is released after the gear-shifting operation. Also, regarding the main gear-shifting apparatus, gear shifting is performed by pressing an upshift switch and a downshift switch provided on a nob of the operation lever. In other words, by pressing an upshift switch 37 in sequence from a first gear stage, gear shifting to an eighth gear stage is achieved one gear stage at a time. Conversely, by pressing a downshift switch for the main gear-shifting apparatus at the position for the eighth gear stage in sequence, it is possible to downshift from the eighth gear stage to the first gear stage. The display of the selected gear stage is performed via a liquid crystal display portion arranged on a gauge panel. The gear shift position of the sub gear-shifting apparatus is displayed in the upper left portion of the liquid crystal display panel, and the gear shift position of the main gear-shifting apparatus is displayed as a mirror image on the right side thereof.